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JOHN JAMIES HOOD, OF LONDON, ENGLAND.

PURIFICATIQN' 03E SULFUR.

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No Drawing.

To all whom it may concern:

Be it known that 1, JOHN Janus Hoon, a subject of the King of Great Britain, residing at 4 Canon'bury Park North, London, England, have invented new and useful limprovements in the Purification of Sulfur, of which the following is a specification.

The object of this invention is to obtain sulfur of high purity from crude native sulfur, such asis contaminated with pitch or other carbonaceous body, or from the impure sulfur obtained by leaching by a suitable solvent what is known as spent oxid in the purification of coal gas.

- According to this invention 1 melt or dissolve in a suitable solvent the impure sulfur and cause the melt or solution to pass through precipitated and ignited tri-hydrate of alumina. Or I may employ the natural analogues of this body, namely, bauxite, which may be contaminated with silica.' Before use, the precipitated oxid is granulated or the native bauxite is broken up and graded by passing it through sieves and then ignited to expel any water or carbonic acid.

Preferably sulfur which does not contain large amounts of pitch or other impurities is melted and passed through ignited bauxite contained in a vessel which is preferably maintained at a temperature of 120 C.

When the filtering material is exhausted, the sulfur adhering to it may be separated by passing steam or a solvent of sulfur into the vessel and then igniting the filtering material to burn off any bodies adhering to it. The filtering material is then ready for. reuse.

When'treating spent oxid I leach it in a suitable filter with carbon bisulfid or other solvent to extract the sulfur together with such other soluble material as may come into solution from the oxid, and the sulfur solution thus obtained is passed through ignited bauxite in a closed filter or a series of filters. The exhausted filtering material may be freed from the sulfur solution by washing with carbon bisulfid and steaming off; the material having been then ignited is ready for re-use.

When treating sulfur in solution, the efiiciency of the above mentioned filtering ma- Specification of Letters Patent.

Patented 24', 15 926 Application filed December 13, 1919. Serial No. 344,730.

terials may be increased by first removing some of the tarry matters by agitating the solution of sulfur, for instance, the solution of sulfur in carbon bisulfid, with a small quantity of strong sulfuric acid whereby a considerable quantity of the tarry matters is eliminated and settles out in the form of a black sludge combined with sulfuric acid.

A. small quantity of water may be added to the solution of sulfur after treatment with sulfuric acid either before or after the tarry matters precipitated by the sulfuric acid have subsided and been removed. The addition of water to the solution has the effect of precipitating a further quantity of impure matters which may be removed from the liquid by filtration or other known methods.

After the separation of the sulfur solution from the impurities, the sulfur solution is passed through the filtering materials as above described.

In the claims, liquid sulfur includes melted sulfur or sulfur in solution alumina includes bauxite.

What I claim is:

l. Purifying sulfur by passing liquidsulfur through ignited alumina.

2. Purifying sulfur by first treating the solution of sulfur with a small quantity of strong sulfuric acid, separating the solution of sulfur from the precipitated impurities and passing it through ignited alumina.

3. Purifying sulfur by first treating the solution of sulfur with a small quantity of strong sulfuric acid, adding a small quantity of water to the solution, removing the precipitated impurities and passing the solution through ignited alumina.

4. Purifying sulfur by first treating the solution of sulfur with a small quantity of strong sulfuric acid, separating the solution of sulfur from the precipitated impurities, adding a small quantity of water to the solution, removing the precipitated impurities and nited alumina.

In testimony that I claim the foregoing as my invention I have signed my name this 24th day of November, 1919.

JOHN JAMES HOOD.

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passing the solution through ig- 

